Science : announces completion of patient recruitment for phase 3 study in severe persistent asthma

Paris, 6 March 2017, 8am

Given the success in recruiting the targeted number of patients, AB Science has decided to continue the study until completion, even in the event of the interim analysis being successful, in order to provide evidence of efficacy in a sufficiently large number of patients for registration. This decision has been communicated to the Independent Data Monitoring Committee (IDMC) prior to the study's interim analysis, which was planned with 50% of the patients.

Consequently, the IDMC has not communicated to AB Science the interim analysis results but has indicated that the study can continue on the basis of the safety data and did not request implementation of the protocol resampling option.

As a reminder, the protocol provided for a resampling option (possibility of doubling the number of patients to be included) to be implemented should any positive trend observed at the interim analysis be insufficient for the study to be successful with the initial number of planned patients, thereby necessitating recruitment of additional patients to obtain a statistically significant demonstration.

Asthma uncontrolled by oral corticosteroid represents the most severe form of asthma (GINA* step V patients that are uncontrolled) and represents a high unmet medical need. The quality of life of these patients is severely impacted, with major reduction in lung function, restrictions on activities of daily living, work absenteeism, night-time awakening several times a week, frequent exacerbations and greater risk of life-threatening asthma exacerbations. The target population in adult patients is estimated at 70,000 in the USA and in the EU.

In order to expand the asthma franchise, AB Science has initiated a new phase 3 study (AB14001) in asthma uncontrolled by high-dose inhaled corticosteroid plus long-acting beta-agonists (LABAs) and with elevated eosinophil level. This study has recruited its first patients. This new indication is much broader and is estimated to affect 1,500,000 adults in the USA and Europe.

Intellectual Property for masitinib is secured in asthma until 2032. The U.S. Patent and Trademark Office has granted a patent (13/983626) relating to methods of treating severe persistent asthma with masitinib. This patent, which expires in 2032, protects to the use of masitinib in the treatment of severe persistent corticosteroid-dependent asthma and severe persistent corticosteroid-resistant asthma.

The first phase 3 trial (AB07015) is a double-blind, randomized, placebo controlled study evaluating the safety and efficacy of masitinib in severe asthma uncontrolled by oral corticosteroids. The primary endpoint

of this study is the rate of severe asthma exacerbations over the treatment period. The duration of treatment predefined by the protocol is 36 weeks. The planned recruitment is for 350 assessable patients.

The second phase 3 trial (AB14001) is a double-blind, randomized, placebo controlled study evaluating the safety and efficacy of masitinib in asthma uncontrolled by high-dose inhaled corticosteroids and with elevated eosinophil level. The primary endpoint of this study is the rate of severe asthma exacerbations over the treatment period. The duration of treatment predefined by the protocol is 36 weeks. The planned recruitment is for 350 assessable patients.

About masitinib

Masitinib is a new orally administered tyrosine kinase inhibitor that targets mast cells and macrophages, important cells for immunity, through inhibiting a limited number of kinases. Based on its unique mechanism of action, masitinib can be developed in a large number of conditions in oncology, in inflammatory diseases, and in certain diseases of the central nervous system. In oncology due to its immunotherapy effect, masitinib can have an effect on survival, alone or in combination with chemotherapy. Through its activity on mast cells and microglia and consequently the inhibition of the activation of the inflammatory process, masitinib can have an effect on the symptoms associated with some inflammatory and central nervous system diseases and the degeneration of these diseases.

About AB Science

Founded in 2001, AB Science is a pharmaceutical company specializing in the research, development and commercialization of protein kinase inhibitors (PKIs), a class of targeted proteins whose action are key in signaling pathways within cells. Our programs target only diseases with high unmet medical needs, often lethal with short term survival or rare or refractory to previous line of treatment in cancers, inflammatory diseases, and central nervous system diseases, both in humans and animal health.

AB Science has developed a proprietary portfolio of molecules and the Company's lead compound, masitinib, has already been registered for veterinary medicine in Europe and in the USA. The company is currently pursuing thirteen phase 3 studies in human medicine in metastatic prostate cancer, metastatic pancreatic cancer, relapsing metastatic colorectal cancer, relapsing metastatic ovarian cancer, first-line GIST, second-line GIST, metastatic melanoma expressing JM mutation of c-Kit, relapsing multiple myeloma, relapsing T-cell lymphoma, severe asthma, amyotrophic lateral sclerosis, Alzheimer's disease and progressive forms of multiple sclerosis. The company is headquartered in Paris, France, and listed on Euronext Paris (ticker: AB).

Further information is available on AB Science's website: www.ab-science.com.

Forward-looking Statements - AB Science

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These forward-looking statements can often be identified by the words "expect", "anticipate", "believe", "intend", "estimate" or "plan" as well as other similar terms. While AB Science believes these forward-looking statements are reasonable, investors are cautioned that these forward-looking statements are subject to numerous risks and uncertainties that are difficult to predict and generally beyond the control of AB Science and which may imply that results and actual events significantly differ from those expressed, induced or anticipated in the forward-looking information and statements. These risks and uncertainties include the uncertainties related to product development of the Company which may not be successful or to the marketing authorizations granted by competent authorities or, more generally, any factors that may affect marketing capacity of the products developed by AB Science, as well as those developed or identified in the public documents filed by AB Science with the Autorité des Marchés Financiers (AMF), including those listed in the Chapter 4 "Risk Factors" of AB Science reference document filed with the AMF on November 22, 2016, under the number R. 16-078. AB Science disclaims any obligation or undertaking to update the forward-looking information and statements, subject to the applicable regulations, in particular articles 223-1 et seq. of the AMF General Regulations.

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*GINA : Global Initiative for Asthma ; http://ginasthma.org